The use of standard electronic modules in future electronic systems places stringent requirements on the thermal interfacing of these units to their ultimate heat sink. As presently configured, the modules are thermally coupled to the chassis side walls containing the heat transfer surfaces through engaging tab extensions, and pressure created by standard type wedge clamps. This technique is satisfactory in designs where the heat flux at the mating surfaces is under 10 watts/in.sup.2. Control of the machine finish on each surface to better than 32 micro inch and flatness variations of under 0.001 inch per inch per surface together with proper dimensional tolerancing of parts result in acceptable temperature gradients across these interfaces. An expression defining this gradiant for surfaces described above and with pressures in excess of 30 psi is: EQU .DELTA.T=0.5.phi.
where .phi.=flux, watts/in.sup.2
and PA1 .DELTA.T=interface delta, .degree.C.
On one type of interface, a 20 watt module results in an interface delta of only 5.degree. C. (each tab area is 1 in.sup.2). However, the introduction of higher power modules such as low voltage power supply units creates flux densities at tab interfaces which far exceed 10 watts/in.sup.2. For these units, it is necessary to increase the number of tabs or the engaging surface area to limit the gradient. A typical arrangement is shown in FIG. 1, where the module heat Q passes internally to the engaging tabs on each end and into the finned heat exchanger walls. The temperature gradient across the interface with this type configuration is an unacceptable 21.degree. C. based on a 100 watt module heat dissipation and an interface area of 1.2 in.sup.2 (0.22.times.5.5") at each end.